Development of Polymer Blend Electrolyte Membranes Based on Chitosan: Dextran with High Ion Transport Properties for EDLC Application.

Solid polymer blend electrolyte membranes (SPBEM) composed of chitosan and dextran with the incorporation of various amounts of lithium perchlorate (LiClO4) were synthesized. The complexation of the polymer blend electrolytes with the salt was examined using FTIR spectroscopy and X-ray diffraction (XRD). The morphology of the SPBEs was also investigated using field emission scanning electron microscopy (FESEM). The ion transport behavior of the membrane films was measured using impedance spectroscopy. The membrane with highest LiClO4 content was found to exhibit the highest conductivity of 5.16 × 10-3 S/cm. Ionic (ti) and electronic (te) transference numbers for the highest conducting electrolyte were found to be 0.98 and 0.02, respectively. Electrochemical stability was estimated from linear sweep voltammetry and found to be up to ~2.3V for the Li+ ion conducting electrolyte. The only existence of electrical double charging at the surface of electrodes was evidenced from the absence of peaks in cyclic voltammetry (CV) plot. The discharge slope was observed to be almost linear, confirming the capacitive behavior of the EDLC. The performance of synthesized EDLC was studied using CV and charge-discharge techniques. The highest specific capacitance was achieved to be 8.7 F·g-1 at 20th cycle. The efficiency (η) was observed to be at 92.8% and remained constant at 92.0% up to 100 cycles. The EDLC was considered to have a reasonable electrode-electrolyte contact, in which η exceeds 90.0%. It was determined that equivalent series resistance (Resr) is quite low and varies from 150 to 180 Ω over the 100 cycles. Energy density (Ed) was found to be 1.21 Wh·kg-1 at the 1st cycle and then remained stable at 0.86 Wh·kg-1 up to 100 cycles. The interesting observation is that the value of Pd increases back to 685 W·kg-1 up to 80 cycles.

Structural, Impedance, and EDLC Characteristics of Proton Conducting Chitosan-Based Polymer Blend Electrolytes with High Electrochemical Stability.

In this report, a facile solution casting technique was used to fabricate polymer blend electrolytes of chitosan (CS):poly (ethylene oxide) (PEO):NH4SCN with high electrochemical stability (2.43V). Fourier transform infrared (FTIR) spectroscopy was used to investigate the polymer electrolyte formation. For the electrochemical property analysis, cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS) techniques were carried out. Referring to the FTIR spectra, a complex formation between the added salt and CS:PEO was deduced by considering the decreasing and shifting of FTIR bands intensity in terms of functional groups. The CS:PEO:NH4SCN electrolyte was found to be electrochemically stable as the applied voltage linearly swept up to 2.43V. The cyclic voltammogram has presented a wide potential window without showing any sign of redox peaks on the electrode surface. The proved mechanisms of charge storage in these fabricated systems were found to be double layer charging. The EIS analysis showed the existence of bulk resistance, wherein the semicircle diameter decreased with increasing salt concentration. The calculated maximum DC conductivity value was observed to be 2.11 × 10-4 S/cm for CS:PEO incorporated with 40 wt% of NH4SCN salt. The charged species in CS:PEO:NH4SCN electrolytes were considered to be predominantly ionic in nature. This was verified from transference number analysis (TNM), in which ion and electron transference numbers were found to be tion = 0.954 and tel = 0.045, respectively. The results obtained for both ion transference number and DC conductivity implied the possibility of fabricating electrolytes for electrochemical double layer capacitor (EDLC) device application. The specific capacitance of the fabricated EDLC was obtained from the area under the curve of the CV plot.

A Polymer Blend Electrolyte Based on CS with Enhanced Ion Transport and Electrochemical Properties for Electrical Double Layer Capacitor Applications.

The fabrication of energy storage EDLC in this work is achieved with the implementation of a conducting chitosan-methylcellulose-NH4NO3-glycerol polymer electrolyte system. The simple solution cast method has been used to prepare the electrolyte. The impedance of the samples was fitted with equivalent circuits to design the circuit diagram. The parameters associated with ion transport are well studied at various plasticizer concentrations. The FTIR investigation has been done on the films to detect the interaction that occurs among plasticizer and polymer electrolyte. To get more insights into ion transport parameters, the FTIR was deconvoluted. The transport properties achieved from both impedance and FTIR are discussed in detail. It was discovered that the transport parameter findings are in good agreement with both impedance and FTIR studies. A sample with high transport properties was characterized for ion dominancy and stability through the TNM and LSV investigations. The dominancy of ions in the electrolyte verified as the tion of the electrolyte is established to be 0.933 whereas it is potentially stable up to 1.87 V. The rechargeability of the EDLC is steady up to 500 cycles. The internal resistance, energy density, and power density of the EDLC at the 1st cycle are 53 ohms, 6.97 Wh/kg, and 1941 W/kg, respectively.

Investigation of Ion Transport Parameters and Electrochemical Performance of Plasticized Biocompatible Chitosan-Based Proton Conducting Polymer Composite Electrolytes.

In this study, biopolymer composite electrolytes based on chitosan:ammonium iodide:Zn(II)-complex plasticized with glycerol were successfully prepared using the solution casting technique. Various electrical and electrochemical parameters of the biopolymer composite electrolytes' films were evaluated prior to device application. The highest conducting plasticized membrane was found to have a conductivity of 1.17 × 10-4 S/cm. It is shown that the number density, mobility, and diffusion coefficient of cations and anions fractions are increased with the glycerol amount. Field emission scanning electron microscope and Fourier transform infrared spectroscopy techniques are used to study the morphology and structure of the films. The non-Debye type of relaxation process was confirmed from the peak appearance of the dielectric relaxation study. The obtained transference number of ions (cations and anions) and electrons for the highest conducting sample were identified to be 0.98 and 0.02, respectively. Linear sweep voltammetry shows that the electrochemical stability of the highest conducting plasticized system is 1.37 V. The cyclic voltammetry response displayed no redox reaction peaks over its entire potential range. It was discovered that the addition of Zn(II)-complex and glycerol plasticizer improved the electric double-layer capacitor device performances. Numerous crucial parameters of the electric double-layer capacitor device were obtained from the charge-discharge profile. The prepared electric double-layer capacitor device showed that the initial values of specific capacitance, equivalence series resistance, energy density, and power density are 36 F/g, 177 Ω, 4.1 Wh/kg, and 480 W/kg, respectively.

Energy Storage Behavior of Lithium-Ion Conducting poly(vinyl alcohol) (PVA): Chitosan(CS)-Based Polymer Blend Electrolyte Membranes: Preparation, Equivalent Circuit Modeling, Ion Transport Parameters, and Dielectric Properties.

Plasticized lithium-ion-based-conducting polymer blend electrolytes based on poly(vinyl alcohol) (PVA):chitosan (CS) polymer was prepared using a solution cast technique. The conductivity of the polymer electrolyte system was found to be 8.457 × 10-4 S/cm, a critical factor for electrochemical device applications. It is indicated that the number density (n), diffusion coefficient (D), and mobility (µ) of ions are increased with the concentration of glycerol. High values of dielectric constant and dielectric loss were observed at low frequency region. A correlation was found between the dielectric constant and DC conductivity. The achieved transference number of ions (tion) and electrons (te) for the highest conducting plasticized sample were determined to be 0.989 and 0.011, respectively. The electrochemical stability for the highest conducting sample was 1.94 V, indicated by linear sweep voltammetry (LSV). The cyclic voltammetry (CV) response displayed no redox reaction peaks through its entire potential range. Through the constructing electric double-layer capacitor, the energy storage capacity of the highest conducting sample was investigated. All decisive parameters of the EDLC were determined. At the first cycle, the specific capacitance, internal resistance, energy density, and power density were found to be 130 F/g, 80 Ω, 14.5 Wh/kg, and 1100 W/kg, respectively.

Compatible Solid Polymer Electrolyte Based on Methyl Cellulose for Energy Storage Application: Structural, Electrical, and Electrochemical Properties.

Compatible green polymer electrolytes based on methyl cellulose (MC) were prepared for energy storage electrochemical double-layer capacitor (EDLC) application. X-ray diffraction (XRD) was conducted for structural investigation. The reduction in the intensity of crystalline peaks of MC upon the addition of sodium iodide (NaI) salt discloses the growth of the amorphous area in solid polymer electrolytes (SPEs). Impedance plots show that the uppermost conducting electrolyte had a smaller bulk resistance. The highest attained direct current DC conductivity was 3.01 × 10-3 S/cm for the sample integrated with 50 wt.% of NaI. The dielectric analysis suggests that samples in this study showed non-Debye behavior. The electron transference number was found to be lower than the ion transference number, thus it can be concluded that ions are the primary charge carriers in the MC-NaI system. The addition of a relatively high concentration of salt into the MC matrix changed the ion transfer number from 0.75 to 0.93. From linear sweep voltammetry (LSV), the green polymer electrolyte in this work was actually stable up to 1.7 V. The consequence of the cyclic voltammetry (CV) plot suggests that the nature of charge storage at the electrode-electrolyte interfaces is a non-Faradaic process and specific capacitance is subjective by scan rates. The relatively high capacitance of 94.7 F/g at a sweep rate of 10 mV/s was achieved for EDLC assembly containing a MC-NaI system.

Metal Complex as a Novel Approach to Enhance the Amorphous Phase and Improve the EDLC Performance of Plasticized Proton Conducting Chitosan-Based Polymer Electrolyte.

This work indicates that glycerolized chitosan-NH4F polymer electrolytes incorporated with zinc metal complexes are crucial for EDLC application. The ionic conductivity of the plasticized system was improved drastically from 9.52 × 10-4 S/cm to 1.71 × 10-3 S/cm with the addition of a zinc metal complex. The XRD results demonstrated that the amorphous phase was enhanced for the system containing the zinc metal complex. The transference number of ions (tion) and electrons (te) were measured for two of the highest conducting electrolyte systems. It confirmed that the ions were the dominant charge carriers in both systems as tion values for CSNHG4 and CSNHG5 electrolytes were 0.976 and 0.966, respectively. From the examination of LSV, zinc improved the electrolyte electrochemical stability to 2.25 V. The achieved specific capacitance from the CV plot reveals the role of the metal complex on storage properties. The charge-discharge profile was obtained for the system incorporated with the metal complex. The obtained specific capacitance ranged from 69.7 to 77.6 F/g. The energy and power densities became stable from 7.8 to 8.5 Wh/kg and 1041.7 to 248.2 W/kg, respectively, as the EDLC finalized the cycles.

Glycerolized Li+ Ion Conducting Chitosan-Based Polymer Electrolyte for Energy Storage EDLC Device Applications with Relatively High Energy Density.

In this study, the solution casting method was employed to prepare plasticized polymer electrolytes of chitosan (CS):LiCO2CH3:Glycerol with electrochemical stability (1.8 V). The electrolyte studied in this current work could be established as new materials in the fabrication of EDLC with high specific capacitance and energy density. The system with high dielectric constant was also associated with high DC conductivity (5.19 × 10-4 S/cm). The increase of the amorphous phase upon the addition of glycerol was observed from XRD results. The main charge carrier in the polymer electrolyte was ion as tel (0.044) < tion (0.956). Cyclic voltammetry presented an almost rectangular plot with the absence of a Faradaic peak. Specific capacitance was found to be dependent on the scan rate used. The efficiency of the EDLC was observed to remain constant at 98.8% to 99.5% up to 700 cycles, portraying an excellent cyclability. High values of specific capacitance, energy density, and power density were achieved, such as 132.8 F/g, 18.4 Wh/kg, and 2591 W/kg, respectively. The low equivalent series resistance (ESR) indicated that the EDLC possessed good electrolyte/electrode contact. It was discovered that the power density of the EDLC was affected by ESR.

Structural, Impedance and Electrochemical Characteristics of Electrical Double Layer Capacitor Devices Based on Chitosan: Dextran Biopolymer Blend Electrolytes.

This report presents the preparation and characterizations of solid biopolymer blend electrolyte films of chitosan as cationic polysaccharide and anionic dextran (CS: Dextran) doped with ammonium iodide (NH4I) to be utilized as electrolyte and electrode separator in electrical double-layer capacitor (EDLC) devices. FTIR and XRD techniques were used to study the structural behavior of the films. From the FTIR band analysis, shifting and broadening of the bands were observed with increasing salt concentration. The XRD analysis indicates amorphousness of the blended electrolyte samples whereby the peaks underwent broadening. The analysis of the impedance spectra emphasized that incorporation of 40 wt.% of NH4I salt into polymer electrolyte exhibited a relatively high conductivity (5.16 × 10-3 S/cm). The transference number measurement (TNM) confirmed that ion (tion = 0.928) is the main charge carriers in the conduction process. The linear sweep voltammetry (LSV) revealed the extent of durability of the relatively high conducting film which was 1.8 V. The mechanism of charge storage within the fabricated EDLC has been explained to be fully capacitive behavior with no redox peaks appearance in the cyclic voltammogram (CV). From this findings, four important parameters of the EDLC; specific capacitance, equivalent series resistance, energy density and power density were calculated as 67.5 F/g, 160 ohm, 7.59 Wh/kg and 520.8 W/kg, respectively.

Electrical, Dielectric Property and Electrochemical Performances of Plasticized Silver Ion-Conducting Chitosan-Based Polymer Nanocomposites.

In the present work, chitosan (CS) as a natural biopolymer was used to prepare nanocomposite polymer electrolytes (NCPEs) in order to reduce plastic waste pollution. The plasticized CS-based NCSPE has been prepared via the solution casting technique. The electrical properties of the films were investigated using AC conductivity, dielectric properties, electric modulus, and electrical impedance spectroscopy (EIS). The obtained results from the dielectric properties and electric modulus study confirm the non-Debye behavior of ion dynamics. The effect of glycerol plasticizer on ionic conductivity of the CS:AgNO3:Al2O3 system was investigated via AC conductivity and impedance studies. The conductivity of the samples was explained based on electrical equivalent circuits and Bode plots. The electrochemical properties such as transfer number measurement (TNM), linear sweep voltammetry (LSV), and cyclic voltammetry (CV) were carried out to inspect the sample suitability for electrochemical double-layer capacitor (EDLC) application. The highest conductivity was 3.7 × 10-4 S cm-1 with the electrochemical stability window up to 2.1 V at room temperature. Through the TNM study, the ionic conductivity of plasticized CS-based NCSPE was confirmed, and ion transport (tion) of the highest conducting sample was found to be 0.985. The activated carbon electrode with the highest conducting sample was employed in the EDLC device fabrication. Accordingly, it can be said that the highest conducting sample had capable performance to be applied in electrochemical device application.

The Study of Plasticized Solid Polymer Blend Electrolytes Based on Natural Polymers and Their Application for Energy Storage EDLC Devices.

In this work, plasticized magnesium ion-conducting polymer blend electrolytes based on chitosan:methylcellulose (CS:MC) were prepared using a solution cast technique. Magnesium acetate [Mg(CH3COO)2] was used as a source of the ions. Nickel metal-complex [Ni(II)-complex)] was employed to expand the amorphous phase. For the ions dissociation enhancement, glycerol plasticizer was also engaged. Incorporating 42 wt% of the glycerol into the electrolyte system has been shown to improve the conductivity to 1.02 × 10-4 S cm-1. X-ray diffraction (XRD) analysis showed that the electrolyte with the highest conductivity has a minimum crystallinity degree. The ionic transference number was estimated to be more than the electronic transference number. It is concluded that in CS:MC:Mg(CH3COO)2:Ni(II)-complex:glycerol, ions are the primary charge carriers. Results from linear sweep voltammetry (LSV) showed electrochemical stability to be 2.48 V. An electric double-layer capacitor (EDLC) based on activated carbon electrode and a prepared solid polymer electrolyte was constructed. The EDLC cell was then analyzed by cyclic voltammetry (CV) and galvanostatic charge-discharge methods. The CV test disclosed rectangular shapes with slight distortion, and there was no appearance of any redox currents on both anodic and cathodic parts, signifying a typical behavior of EDLC. The EDLC cell indicated a good cyclability of about (95%) for throughout of 200 cycles with a specific capacitance of 47.4 F/g.